Fuse indicator



Feb. 17, 1931.

F. c. LA MAR 1,793,103

FUSE INDICATOR Filed Nov. 15, 192? INVENTOR Patented Feb. 17, 1931 PATENT OFFICE FRANK C. LA MAR, OF NEW YORK, N. Y.

FUSE INDICATOR Application filed November 13, 1929. Serial No. 406,952.

This invention relates to electrical fuses, especially to electrical fuses of the cartridge type, and more particularly to an indicator for such fuses which acts to give information as to the integrity of the fusible element.

lt is well understood by those skilled in the electrical art that safety requires all circuits which carry or are capable of carrying an appreciable amount of current have inserted safety devices in them to prevent an excessive flow of current under abnormal conditions.

A commonsafety device is the well known l5 fuse made of a strip of metal which will melt upon the flow therethrough of an undesirably .heavy current. y up Fuses are made of many `forms ramongst which the cartridge fuse is a common type.

The cartridge fuse may be either of the ferrule type or the knife blade type. In either case. if it is of the renewable type, there is no convenient and desirable means of simple form by which the fact that the'fusible metal has melted may be indicated except by removing the fuse from its position and disassembling it.

A principal object of applicants invention is the provision of a means by which the integrity of the fusible elements of a fuse may be ascertained by a visual inspection without disassembling the fuse or disturbing the position thereof.

A further object of applicants invention is the provision of a means by which the integrity of the fusible element of a fuse may be ascertained by a visible inspection without disassembling the fuse or disturbing the position thereof, which maybe applied to the common forms of ferrule type fuses or knife blade types including a ferrule or cap, by a simple manual-operation, not involving permanent fastening means.

Other objects and advantages will appear as the description of the particular physical embodiment selected to illustrate the invention progresses and the novel features of the invention will.be particularly pointed out in the appended claims.

In describing the invention in detail and the particular physical embodiment selected to illustrate the invention, reference will be i had to the accompanying drawings, and the several viewsthereof, wherein like characters of reference designate corresponding parts, and in which:

Figure l is a side elevational view of a cartridge fuse of the usual forni having an indicator of my invention in place thereon; Fig. 2 is a longitudinal sectional view of the indicator as shown in Fig. 1; Fig..3 is an end view of the indicator as shown in Fig. 1.

1 designates the hollow tube of insulating material forming the well known body of the ordinary fuse. 2 and 3 designate metallic ferrules positioned upon the ends of the body,

as is usual in both ferrule and knife blade types. 4 and 5 designate caps, one on each of the ferrules. 6 designates the usual fusible link of considerable current carrying capacity positioned lin the interior of the cartridge and forming electrical connection between 2 and 4: and 3 and 5.

The indicator for giving .a visual indication of the integrity of the fusible link 6 is positioned on the outside of the cartridge as a fusible wire 7 of relatively small current carrying capacity compared with the fusible link 6. The fusible wire 7 is preferably contained within a transparent tube 8, preferably ofglass, formed with metallic end thimbles 9 and 10 to each of which an end of the fusible wire 7 is electrically connected.

The wire including the enclosing tube and metallic thimbles is supported between and upon metallic brackets 11 and 12, one at each end thereof. These brackets are mounted upon an insulating bar 13 and are held thereto in any suitable or appropriate manner as by rivets 14 and 15.

The bar 13 also carries the clips 16 and 17 which are formed to partially embrace the insulating body 1. They are formed of resilient material so that they may be pushed in place on the body 1 and thereafter by their resiliency will maintain themselves in place. The clips 16 and 17 are attached to the bar 13 in any suitable and appropriate manner as by rivets 18-and 19.

Various methods may be used to electrical- Y i ly connect the ferrules, as 2 and 3, tothe brackets as 11 and 12. In the form shown, i

conducting bars 20 and21 are utilized'. These bars each rest upon a ferrule as 2 and pass under the insulating -bar 13 and between a clip` as 16 and the bar. Each conducting bar is held in place by the same rivets which are used to hold the lbrackets as 11 and the clips as 16 in place.

The indicator of my invention is easily slipped in place by a single manual movement as the clips 16 and 17 will spread suiciently to allow the device to be pushed in place on a cartridge fuse andatter being pushed in place the clips 16 and 17 by their resiliency will hold it in place. N

As long as the fusible link is intact the fuse wire 7 will be intact but after the fusible link 6 has been disrupted by an abnormal current How therethrough the fuse wire 7 will become disrupted. This fact may be easily observed without removing the cartridge fuse from the clips in which it is ordinarily held.

Although I have described one particular physical embodiment of my invention, and explained the construction and principle thereof, nevertheless, I desire to have it un'- derstood that the particular form selected is merely illustrative and does not exhaust the possible physical embodiments of the idea ofy means underlying my invention.

What I claim as new and desire to secure by Letters Patent ofthe United States, is:

1. In an indicator for a cartridge fuse formed with metallic ferrules, one at each end, in combination: an insulating bar; two clips, one at each end ofthe bar; two metallic brackets, onel adjacent each end of the bar; an/ enclosed fuse wire of relatively small current carrying capacity electrically connecting the brackets; two electrical conductors, one at each end of the bar each connecting a ferrule with a bracket.

2. In an indicator for a cartridge fuse formed with a metallic ferrule at each end, in combination.: a transparent tube; a fuse wire Within the tube; metallic thimbles, one at each end of the tube to which the ends of the fuse wire are connected; two metallic brackets, one engaging each end of the tube; an iny sulating bar supporting the brackets; two

clips, one at each end of the bar adapted to partially embrace a. cartridge fuse; and two metallic bars, one at each 'end of the insulating bar and extending beyond the ends of the insulating'bar and electricallycomlected to the metallic thimbles.

FRANK C. LA MAR. 

